Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere
NeQuick2 is a three-dimensional ionospheric electron density empirical model that uses numerical integration to calculate the total electron content along any line-of-sight (LOS). As one of the most commonly used three-dimensional ionospheric models, it is necessary to objectively evaluate the accur...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-08-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/16/4124 |
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| author | Lingxuan Wang Erhu Wei Si Xiong Tengxu Zhang Ziyu Shen |
| author_facet | Lingxuan Wang Erhu Wei Si Xiong Tengxu Zhang Ziyu Shen |
| author_sort | Lingxuan Wang |
| collection | DOAJ |
| description | NeQuick2 is a three-dimensional ionospheric electron density empirical model that uses numerical integration to calculate the total electron content along any line-of-sight (LOS). As one of the most commonly used three-dimensional ionospheric models, it is necessary to objectively evaluate the accuracy and stability of NeQuick2 over a long period, especially over the mid-latitudes of the northern hemisphere where most of the ground-based GNSS stations are distributed. Therefore, different methods are used in this study to evaluate the accuracy of the NeQuick2 model from 2008 to 2021, including comparison with the International Global Navigation Satellite System Global Ionosphere Maps (IGSG), Jason2 Vertical Electron content (VTEC), and self-consistent evaluation. The comparison with IGSG shows that the standard deviation (STD) value is about 2.59 TECU. The accuracy of the IGSG and NeQuick2 model over ocean regions shows that the bias of IGSG is more significant than that of the NeQuick2 model. The mean STD value is 2.09 TECU for IGSG, and the corresponding value is 3.18 TECU for the NeQuick2 model, which is about 50% worse than IGSG. The dSTEC assessment results indicate that the variation in bias for IGSG is more stable than that of the NeQuick2 model. The mean STD value is 0.86 and 1.52 TECU for IGSG and NeQuick2 model, respectively. The conclusion could be made that NeQuick2 model represents the average ionosphere electron content and its accuracy fluctuates with solar conditions. Compared with the IGSG, the NeQuick2 model always underestimates TEC value, especially in low solar activity periods and compared with Jason2, the TEC values obtained by NeQuick2 model are overestimated, but the degree of overestimation is smaller than that of IGSG. |
| first_indexed | 2024-03-09T09:50:21Z |
| format | Article |
| id | doaj.art-ccb75804546243309de1ff490c8f76ac |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T09:50:21Z |
| publishDate | 2022-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-ccb75804546243309de1ff490c8f76ac2023-12-02T00:15:59ZengMDPI AGRemote Sensing2072-42922022-08-011416412410.3390/rs14164124Evaluation of NeQuick2 Model over Mid-Latitudes of Northern HemisphereLingxuan Wang0Erhu Wei1Si Xiong2Tengxu Zhang3Ziyu Shen4School of Geodesy and Geomatics, Wuhan University, Wuhan 430072, ChinaSchool of Geodesy and Geomatics, Wuhan University, Wuhan 430072, ChinaSchool of Geodesy and Geomatics, Wuhan University, Wuhan 430072, ChinaSchool of Resources Environmental Science and Engineering, Hubei University of Science and Technology, Xianning 437100, ChinaSchool of Resources Environmental Science and Engineering, Hubei University of Science and Technology, Xianning 437100, ChinaNeQuick2 is a three-dimensional ionospheric electron density empirical model that uses numerical integration to calculate the total electron content along any line-of-sight (LOS). As one of the most commonly used three-dimensional ionospheric models, it is necessary to objectively evaluate the accuracy and stability of NeQuick2 over a long period, especially over the mid-latitudes of the northern hemisphere where most of the ground-based GNSS stations are distributed. Therefore, different methods are used in this study to evaluate the accuracy of the NeQuick2 model from 2008 to 2021, including comparison with the International Global Navigation Satellite System Global Ionosphere Maps (IGSG), Jason2 Vertical Electron content (VTEC), and self-consistent evaluation. The comparison with IGSG shows that the standard deviation (STD) value is about 2.59 TECU. The accuracy of the IGSG and NeQuick2 model over ocean regions shows that the bias of IGSG is more significant than that of the NeQuick2 model. The mean STD value is 2.09 TECU for IGSG, and the corresponding value is 3.18 TECU for the NeQuick2 model, which is about 50% worse than IGSG. The dSTEC assessment results indicate that the variation in bias for IGSG is more stable than that of the NeQuick2 model. The mean STD value is 0.86 and 1.52 TECU for IGSG and NeQuick2 model, respectively. The conclusion could be made that NeQuick2 model represents the average ionosphere electron content and its accuracy fluctuates with solar conditions. Compared with the IGSG, the NeQuick2 model always underestimates TEC value, especially in low solar activity periods and compared with Jason2, the TEC values obtained by NeQuick2 model are overestimated, but the degree of overestimation is smaller than that of IGSG.https://www.mdpi.com/2072-4292/14/16/4124ionosphere modelGlobal Navigation Satellite System (GNSS)ionosphere monitoringTotal Electron Content (TEC)NeQuick2 modelGIM |
| spellingShingle | Lingxuan Wang Erhu Wei Si Xiong Tengxu Zhang Ziyu Shen Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere Remote Sensing ionosphere model Global Navigation Satellite System (GNSS) ionosphere monitoring Total Electron Content (TEC) NeQuick2 model GIM |
| title | Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere |
| title_full | Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere |
| title_fullStr | Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere |
| title_full_unstemmed | Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere |
| title_short | Evaluation of NeQuick2 Model over Mid-Latitudes of Northern Hemisphere |
| title_sort | evaluation of nequick2 model over mid latitudes of northern hemisphere |
| topic | ionosphere model Global Navigation Satellite System (GNSS) ionosphere monitoring Total Electron Content (TEC) NeQuick2 model GIM |
| url | https://www.mdpi.com/2072-4292/14/16/4124 |
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